22 November 2023
Cancer is the leading cause of death in Australia, claiming almost 50,000 lives in 2019.
The most common treatments for cancer include chemo and radiation but they often harm healthy cells as well cancer cells. Many patients also become resistant to cancer drugs, in a bit the same way they would develop antibiotic resistance. CAR-T therapy is a new type of therapy that has shown stunning responses in certain blood cancers and might be replicable in other types of cancers as well. It cured Australian actor Tom Long after he had been given three months to live and had exhausted all other options for his multiple myeloma.
Here’s how it works.
Using the patient’s own T-cells to fight cancer
CAR-T therapy works by taking immune cells from the patient’s body that fight infection – called T-cells – and training them up outside of the body to recognise the cancer. They’re then grown in large numbers and reinjected into the patient whereby they can track down and kill the patient’s cancer cells.
Here is a normal T-cell. T-cells are the cells in your body that find and kill foreign invaders, be it a virus, a bacteria or even a cancer cell. Most of the cancer cells in your body get picked up by the T-cells, and you never get to know about them.
But unfortunately for cancer patients, their cancer cells have found a way of evading the surveillance of their T-cells.
CAR-T therapy is all about activating those docile T-cells by adding special receptors to them that can find cancer cells and kill them. These special receptors are called Chimeric Antigen Receptor (CAR).
Here is a CAR-T cell – an engineered T Cell with receptors that can find cancers and kill them.
How patients are treated with CAR-T cell therapy:
- Firstly, the patient’s own blood is collected.
- Then their immune cells (T-cells) are isolated and removed from the body.
- The T-cells are genetically manipulated with a receptor that enables them to specifically recognize and kill cancerous cells in the body. The change turns them from docile T-cells into sniffer dogs that can sniff out the cancer and attack it. These cancer receptors are called chimeric antigen receptors (CAR). Added onto immune cells called T-cells, they form CAR-T cells.
- Still outside the patient’s body, millions of new CAR-T cells are grown.
- The CAR-T cells are then injected back into the patient, where – like trained assassins – they locate and then kill cancer cells
Harnessing the properties of the patient’s natural immune system, these CAR-T cells later produce “memory T cells” – meaning that these assassins hang around the body, ready to find and kill any cancer cells that may return.
The future of CAR-T
CAR-T cell therapy has been extensively tested on certain blood cancers, producing some truly incredible results.
In trials on B cell acute lymphoblastic leukemia, tests produced up to a 90% complete remission rate. These success rates were previously unheard of before CAR-T.
Initially, making CAR-T is difficult because it involves using the patient’s own blood cell but people are looking at off-the shelf solutions where T-cells can be manipulated more quickly and at a lower cost. This is as crude as CAR-T is ever going to get. It’s only going to improve from this point.
Clearly, the first company to crack some of these challenges in CAR-T is going to be a game-changer for the industry and for cancer patients.